While 2024's live action Avatar series was met with measured 'mehs' and the animated movie that was meant to come out this year has been pushed back, I can see both why Nickelodeon would be seeking as much marketing as possible, and why Wizards would assume the time was ripe for a tie-in set
Target creature gets -1/-1 until end of turn for each permanent of the chosen type you control
It has a lot of the cheapest, most efficient sources of repeatable proliferate, not to mention the only proliferate-doubler in Tekuthal, Inquiry Dominus
There is a Pikachu right smack bang in the middle of the Pikachu V-union card, which means that its various body parts have been spread across the four cards like pieces of a great key that open some mighty, Pikachu-shaped lock
Many turn to Amazon, and it turns out they offer a decent selection
If some of the targets become illegal for Mythos of Vadrok, the original division of damage still applies, but the damage that would have been dealt to illegal targets isn't dealt at all